The prior art includes wheel hubs for vehicles, including medium and heavy-duty trucks, trailers and buses. In one embodiment, the hubs include a stud pilot construction. Studs are passed through a flange of the hub and may be used for centering the brake drum and wheels which are mounted on the hub. In some prior art systems, the studs are used for centering only one of the wheel and drum, typically the wheel.
U.S. Pat. No. 5,739,684 C1 issued to Burns and is assigned to the assignee of the present invention. Burns shows a prior art hub with a drum and wheel pilot arrangement. The hub is typically cast or forged and then machined to form a plurality of drum pilots which engage the corresponding pilot on the brake drum, and to form a plurality of wheel pilots which each engage the corresponding pilot on the wheel or wheels. The bolts used to mount the brake drum and wheel are not used to center the drum and wheels, rather the hub pilots are used to center the drum and wheels with respect to the hub. Typically the hub is machined with the drum pilot having a radius which is larger than the radius of the wheel pilot. Pairs of wheel pilots and drum pilots may be longitudinally aligned with one another and form a continuous machined surface having two right angles, the first separating the wheel pilot and the drum pilot. The second right angle separating the drum pilot from the hub flange. In any event, each pilot is associated with at least one right angle.
As suggested before, the right angles in the pilot construction are formed by a machining process. The prior art pilot construction incorporates a machined radius into the part. The machined radii introduce stress risers in the area of the pilots. The stress risers decreases fatigue life of the hub. The stress risers can be compensated by strengthening the hub such as by increasing the thickness of the cylindrical wall of the hub.
Industry trends and recent developments in hub technology have lead to lighter hub construction. Unfortunately, the light weight hub construction impacts adversely on the stress risers associated with the pilot construction.
It is desirable to provide a hub pilot construction which is not associated with a decreased fatigue life. It is also desirable to provide a pilot construction which does not produce stress risers in the area of the pilot construction. It is further desirable to provide a hub construction which does not have the associated stress risers and which is light weight. It is further desirable to provide a casting where pilots are used at the junction where a flange is joined to a cylindrical body and without producing stress risers.